Sanding Scratches In Wood

[bcjim]

I stripped my guitar body by sanding using 60, 120, and 220 paper. I noticed that there are scratches, some pretty deep in the wood. Do I need to use a coarser paper to get the scratches out then use the finer paper again?

[Southpa]

Yes, thats about the easiest way to work out those areas. But I would start with about 100 grit. Rule of thumb is to sand with the grain at all times. For end grain areas pick a direction and don't deviate from that direction of sanding. 60 grit is used for overall shaping and can produce serious scratches across the grain. Once you've got all your rough edges and uneven surfaces dialed in there is no longer a need for 60 or 80 grit.

I've also learned my lesson when using a rotary palm sander with coarse grit. It makes little spiral curly-cues all throughout the wood that are difficult to remove. The problem is they are very hard to see...until you apply your clearcoat.

Edited April 2, 2005 by Southpa

[Doc]

Good to see that you're still at it. Tell yourself " I will not give up to an inanimate object."

Anything under 120 grit is really for removing wood. I never go coarser than 80 for this kind of woodworking.

Each grit puts it's own scratches in and erases the scratches form the previous, hopefully coarser grit. It sounds like you have 60 grit type scratches and you'll need to gradually work them out. 80, 120, 150. 180, 220

Use each grit until all of the scratches are the same size. The size produced by that particular grit, and all of the scraches from the previous grit are gone.

Use a sanding block unless you're really good. I have over twenty five years of doing this stuff for a living and still usually use a backer block.

Random orbital sanders are great, but they have to be moved along at the right speed. When you're using them right they self erase most of the little corkscrew swirls. Too slow and they eat your wood up. Too fast and little swirls that don't show until you're staining.

Never sand cross grain until you're using really fine grit. Like 180. Then wet your wood, let it dry so the little nibs pop up. Then sand first at a 45 degree angle to cut off the nibs. After that sand with the grain to get out any cross grain scratches.

[thedoctor]

Doc, I never wet the wood to raise nubs or whatever because I was told years ago that the wood takes finish differently and hides lines from sanding until the finish is put on. Please realize, this is OLD info that I took at it's word and have never questioned. Maybe I should. You sure seem to have a good, straight-forward approach to wood finishing.

[DannoG]

Sounds like we need a third opinion. Paging Dr. Flexner to the woodshop...

[Doc]

Don't soak it down just go over it with a damp sponge. This will usually make the sanding lines and other little uglies more visible before staining when they're easier to correct. As long as you don't wet it too much and let it dry all the way it shouldn't interfere with your staining.

If you're using a water base product to finish you pretty much have to do this.

Nice to see someone has actually read Flexner's book. I agree with about 90% of what he says.